This invention relates to an on-demand type ink jet head in which ink is ejected from a nozzle for printing.
Conventionally, in the Japanese Laid-Open Patent Publication No. 60(85)-129263, a common ink chamber is formed on an upper surface of a base plate and connected to each pressure chamber through a plurality of ink supplying channels. Each pressure chamber is connected to an associated nozzle through a connecting channel and the components from the common ink chamber up to the respective connecting channels are formed in one plate. Each nozzle is provided at an extremity of the associated channel in a direction perpendicular to the connecting channel. In a vibrating plate bonded to the passage base plate, an ink ejecting means such as a piezoelectric element is provided at the corresponding position to the pressure chamber. The ink supplying channels and the connecting channels in the vicinity of the nozzle are narrower than other portions.
In the case where the vibrating plate is bonded to the passage base plate, it is conventional to bond them together with adhesive agents. However, this suffers from clogging troubles of adhesive agents in narrow portions such as ink supplying channels and connecting channels in the vicinity of the nozzle. Accordingly, instead of adhesive agents, solvents or dope cements are sometimes used. In this case, however, some solvents or dope cements would flow into the channels, thereby changing the ejection characteristics of the ink droplets, resulting in remarkable variation in flow resistance of channels. In the end, this leads to the variation in efficiency of ink ejection of the respective nozzles. Specifically, the narrow portions such as the ink supplying channels and the connecting channels would largely affect the ink ejection characteristics. Accordingly, unless the narrow portions are formed with high precision, the printing quality would be remarkable degraded.